1. Field of the Invention
The present invention relates to a method of forming a metal line in a semiconductor device and, more particularly, to a method of forming a metal line in a semiconductor device capable of improving an electro migration (EM) characteristic of the metal line.
2. Discussion of Related Art
With increase in the degree of integration of a semiconductor device, in order to reduce resistance of a metal line, it has been tried to form the metal line out of metal material having a lower resistivity. Recently, it was tried to form the metal line out of copper, but there was a problem that the copper has a lower resistivity but a poor EM characteristic.
It is tried to inject Zr into a metal line by using a physical vapor deposition method so as to improve the EM characteristic of the metal line. Zr is an element having little solubility into metal materials (in particular, Cu) and is known to be capable of improving the EM characteristic of a metal thin film (in particular, a Cu thin film). On the other hand, although addition of Zr may increase the resistance of the metal thin film, it is known that a small amount of addition of Zr does not increase largely the resistivity of the metal thin film.
However, with increase in the degree of integration of a device, since Zr is not injected into via hole portions of a narrower and deeper dual damascene pattern in the course of injecting Zr using a PVD method, it is difficult to improve the EM characteristic in via plug portions.